1. Field of the Invention
The present invention relates to a method of measuring a subject's physical strength and an apparatus therefor in which the oxygen uptake based on 75% HRmax (75% of the patient's maximum heart rate) is estimated so that the physical strength of the subject based on oxygen uptake can be evaluated over a wide range of ages safely and accurately and within a range in which a comparison can be made with other measured values.
This application claims priority from Japanese Patent Application No. Hei 4-259655, the disclosure of which is incorporated herein by reference.
2.Description of the Related Art
Known methods of measuring physical strength, include those in which the power of output by a subject such as PWC75% HR max (load at 75% of maximum heart rate) (Japanese Patent Post-Examination Publication No. Hei-1-42694), PWC170, PWC150, PWC130 or the like, is used for evaluation. Also, a method in which the maximum oxygen uptake is obtained through estimation based on the measurement of physical strength under maximum oxygen uptake so that the measured value of physical strength under maximum oxygen uptake is used for evaluation is known (Japanese Patent Unexamined Publication No. Hei-4-26413).
However, while the former method is easy to apply, it has a disadvantage in that the power, as an evaluation of physical strength, measured by one measuring apparatus cannot be easily converted into the power measured by another measuring apparatus and therefore the power is not good for a general index because the various measuring apparatus are different in efficiency depending on the type thereof (e.g., treadmill, bicycle, ascending stairs, and so on).
The latter method uses the oxygen uptake of a subject as an evaluation so that the difference between different apparatuses is comparatively small and the oxygen uptake can be used as a general index. In order to actually measure the oxygen uptake, however, it is necessary to cause the subject to assume all out and therefore the oxygen uptake is not a good evaluation index for middle aged and older subjects. Further, when a step-like load is used, there are difficulties in that, for example, the load changes suddenly so that the subject's pulse is disturbed and it is difficult to finely adjust the load at the end of exercise.
Further, recently, an aerobic threshold (AT) is used as an index for measuring physical strength since the maximum oxygen uptake method is not entirely safe. However, it is not easy to detect AT. Accordingly, the judgment has been performed based on a plurality of judging factors or various algorithms such as a V-slope method corresponds to an algorithm for automatically detecting a point (for example, an inflection point of VCO.sub.2 /VO.sub.2, a point where VE/VO2 increases suddenly while VE/VO2 has no change) and so on. However, currently it is necessary to use more than one of the above criterion in order to make an accurate determination and thus a determination must be made from many points. In addition, a device for analyzing exhalation is expensive.
There remains therefore a question as to whether or not the maximum oxygen uptake is a useful strength index when it is estimated.